Frequently Asked Questions - Asian Cycad Scale

The Parasitic Wasp

Sago Palms

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Where did the Asian cycad scale come from?

Asian cycad scale originates in Thailand and southern China. It is believed to have been accidentally introduced into Florida through the legal importation of cycads.

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Where was this pest discovered?

Infestations of this scale insect have been moving rapidly across the state since this pest was discovered in the mid-1990's near Miami.

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What plants does this insect attack?

King & Queen sago are the two primary species. It has been observed on several other cycads, but does not attack them as severely. A list of other species of cycads that are reported to be attacked are listed at the Featured Creatures website.

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Why is the Asian Cycad Scale such a big problem?

There are several reasons this pest is difficult to control. It has no natural enemies, It reproduces very quickly, the crawler stage can move on the wind, and it can hide down in the root system of the plant.

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How do I know if I have the Asian Cycad Scale?

There are 2 ways to know if the scale on your sago is Asian cycad scale:

  1. Look at the insect under a microscope and compare the image to the Asian Cycad Scale photos on this website.
  2. Compare your plants to the Asian Cycad Scale Infestation photos on this website.

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Why is this pest so difficult to control?

  • In Florida, this pest has no natural enemies to help control it.
  • It reproduces very quickly
  • It can move on the wind
  • It can live on the roots of sagos

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Has the cold winter stopped the scale?

We don't know for sure, but the fact that the scale can live on the roots of sagos would suggest that it could easily overwinter.

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How does the scale move from plant to plant?

The Asian cycad scale can spread in at least 2 ways:

  1. By the movement of infected plants or plant debris.
  2. On the wind from plant to plant.

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What's being done by the government about this pest?

Release of parasitic wasps, and educational efforts to wholesale and retail nursery owners, horticulture service providers and to homeowners.

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How do I control the Asian cycad scale?

There is no clear definitive answer to that question. Research results have been mixed. Insecticides currently being used include:

  • Horticultural oils.
  • Combinations of horticultural oil and Malathion (sold as a premixed concentrate or mixed together using label rates).
  • Contact insecticides like Malathion.
  • Systemic insecticides using the active ingredients: Acephate, Di-Syston®, and Imidacloprid.

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How often should I use these chemicals?

In the little research that has been done, it was noted that within 28 days of hatching, Asian cycad scale could begin laying eggs in warmer weather. To prevent new generations of scale from hatching and bring this pest under control, spray every other week in warmer weather (above 70° F) and once a month in colder weather (below 70° F).

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How long should I continue spraying?

We truly don't know how long it will take to establish the parasitic wasp. We hope that within a year or two we'll start to see some results from the wasp.

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If there are no natural enemies, where did the wasps come from?

Florida scientists traveled to Thailand and China to identify and collect parasites and predators of this scale.

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Will the parasitic wasp sting people?

No. The wasp is about the size of the period at the end of this sentence and no threat to people.

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Is it environmentally safe to release this wasp?

APHIS (Animal & Plant Health Inspection Service), part of the US Department of Agriculture, conducted an environmental assessment to consider the effects of and alternatives to release of parasitic and predaceous insects. they determined that there is no evidence that the release of these organisms would have any adverse effects. Over the last several decades, several species of these organisms have been successfully introduced into the US for control of other scale with no adverse impacts reported.

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Will I see the parasitic wasps on my sago?

Probably not. They're almost too small to be seen.

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How soon should we see results from the parasitic wasp?

No one really knows. It will probably take a couple of years at best.

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I've heard that the only thing to do is to dig up infested sagos. Is that true?

This pest can be controlled with chemicals, however it will take thorough and methodical treatment, possibly for several years. The real issue is whether or not the sago is worth the time and effort to the owner.

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Are other plants or palms affected?

This scale is not known to be a problem of other plants or palms. Sagos are not really palms. They are actually in the family of plants known as cycads that are completely unrelated to palms but look similar.

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Will my sagos die if left untreated?

Yes. The research indicates that that Asian cycad scale does kill sagos. In some cases the sagos were killed within a year of being infested.

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What should I do to protect sagos that haven't yet been infested?

Follow the treatment and schedule recommended above.

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